Both paging systems and cellular radiotelephone systems are widely used forms of communication. The systems allow individuals to keep in contact with the home or office while away.
The paging system is typically a one way radio communication system. An individual wishing to contact someone with a pager usually calls a central telephone number to access the central paging control. The central paging control is either automatic or operated by a human operator.
If the central paging control is automatic, the caller keys in the number assigned to the individual pager they wish to reach. Once that pager is accessed, the caller can either leave a voice message for the paged individual or key in the telephone number to be displayed on the pager's display. Some systems may also allow both types of paging.
If the central paging control is operated by a human operator, the caller typically tells the operator the number of the pager and the message. The operator then pages the individual, and relays the message when the paged individual calls the operator.
Once paged, the individual must find a telephone to answer the page. This problem can be solved by the paged individual carrying a cellular radiotelephone. The cellular radiotelephone allows a mobile user to place a call anywhere within an area covered by the cellular communications system antennas. The cellular radiotelephone allows the user to access the landline telephone system to conduct two way telephone conversations. The cellular radiotelephone user can also receive telephone calls on the radiotelephone.
The pager solves some of the problems of the cellular mobile radiotelephone system. One problem is that if the radiotelephone is turned off or the user is away from the radiotelephone when a call is made to that device, the call will be missed. Another problem is that the radiotelephone user typically pays for incoming as well as outgoing calls. If an unwanted call is made to the radiotelephone, the radiotelephone user must pay for it.
A pager allows the radiotelephone user to receive the number of the calling party whether or not he is near the radiotelephone. Additionally, the user can use the pager to screen incoming calls to determine which telephone number to call back, thereby eliminating the charges for unwanted calls.
While the pager solves some of the limitations of the cellular radiotelephone and vice versa, this creates the problem of carrying two communication devices to remain in contact while moving about an area. An example of a solution to this problem in U.S. Pat. No. 4,747,122 to Bhagat et al., assigned to Mobile Communications Corporation of America, for a mobile paging call back system. This device combines an entire radio pager and radiotelephone linked through an automatic dialer. Because of the redundant hardware and the extra automatic dialer required, this device is large and heavy and does not allow continuous availability of both paging and radiotelephone functions away from the mobile installation. There is a need therefore for a single, small, lightweight, portable device combining the advantages of both the cellular radiotelephone and the pager.